As Cyclone Vardah made landfall near Chennai at around 2pm, a release from the Tamil Nadu government said two people had died.
S Balachandran, Director of Area Cyclone Warning Centre said it will take four hours for the cyclone to cross Chennai.
Chennai has witnessed wind speeds gusting up from 110kmph to 140kmph.
The Tamil Nadu government had earlier issued an advisory urging people to stay indoors until 4pm. The state also appealed to those who were outdoors to find a safe place and stay put.
Cyclone Vardah has hit flight and train services in Chennai. With planes being unable to take-off and land, 25 flights have been diverted, 9 delayed and 5 flights cancelled.
IMD in a statement issued at 1 pm said that wind speeds will remain at 100-120 kmph until 5.30 pm, but heavy winds will be experienced through the night (60-65 kmph).
Southern Railways says electrical overhead lines were severely impacted by the cyclone. Urgent steps being taken for restoration, officials said.17 trains have been cancelled.
Chennai Airport has also suspended operations till 6pm.
13 NDRF teams have been deployed across Tamil Nadu and Andhra Pradesh. Seven army columns on standby. Four teams of SDRF teams are also on ground.
One column has already been requisitioned and is moving to be deployed at Tiruvallur.
Naval ships, INS Shivalik and INS Kadmatt have been deployed to Chennai from Vishakhapatnam with medical teams and relief material on board. Naval officials also said 30 diving teams are ready to be flown in as required
National Disaster Management Authority said all precautions have been taken at Kalpakkam atomic power station.
People living in Ennore and Palaverkadu were asked to evacuate. 8000 people have been taken to 54 relief centres in Tamil Nadu. The total number of relief centres are 95. As of 1.30pm, 260 trees had fallen and 190 had been removed. Also 37 electricity poles fell due to the wind.